Enhanced photo-catalytic cells

ABSTRACT

According to an embodiment of the present invention, an apparatus for ionizing air includes a first reflector and a first target. The first reflector receives direct UV energy (from a UV emitter) and reflects it to form reflected UV energy. The first target has an inner face that also receives direct UV energy (from the UV emitter). The first target also has an outer face that receives the reflected UV energy from the first reflector. The faces of the first target are coated with a photo-catalytic coating. The first target may also have passages between the faces.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 13/225,812 filed on Sep. 6, 2011, and is a continuation-in-part of U.S. patent application Ser. No. 13/115,546 filed on May 25, 2011, and claims the benefit of U.S. Provisional Patent Application No. 61/380,462 filed on Sep. 7, 2010, all of which are herein incorporated by reference in their entireties.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[Not Applicable]

MICROFICHE/COPYRIGHT REFERENCE

[Not Applicable]

BACKGROUND OF THE INVENTION

The present invention generally relates to methods and apparatuses for producing an enhanced ionized cloud of bactericidal molecules.

Photo-catalytic cells may be employed to produce bactericidal molecules—such as cluster ions—in airflow passing through the cells. The cells may be positioned to ionize air that may then be directed into a target environment, such as an enclosed space or room. Emerging molecules from the cells may have a bactericidal effect on various bacteria, molds or viruses which may be airborne in the room or may be on surfaces of walls or objects in the room.

Typically, such cells may be constructed with a target including or coated with a photo-catalytic coating and surrounding a broad spectrum ultra-violet (“UV”) emitter. This combination can produce an ionized cloud of bactericidal molecules. The target may be coated with titanium dioxide as well as other elements. As air passes through or onto the target, UV energy striking the titanium dioxide may result in a catalytic reaction that may produce the desired cloud of bactericidal molecules within the airflow. These molecules—upon contact with any bacteria, mold, or virus—may kill them.

Effectiveness of a photo-catalytic cell may be dependent on the concentration of the bactericidal molecules. Furthermore, it may be desirable to have higher concentrations of cluster ions as compared to oxidizers. Consequently, it may be desirable for improved photo-catalytic cell designs to improve the efficiency of cluster ion generation.

BRIEF SUMMARY OF THE INVENTION

According to an embodiment of the present invention, an apparatus for ionizing air includes a first reflector and a first target. The first reflector receives direct UV energy (from a UV emitter) and reflects it to form reflected UV energy. The first target has an inner face that also receives direct UV energy (from the UV emitter). The first target also has an outer face that receives the reflected UV energy from the first reflector. The faces of the first target are coated with a photo-catalytic coating. The first target may also have passages between the faces. These passages may pass direct UV energy from the UV emitter to the first reflector. In an embodiment, the first reflector is a specular reflector or may have a curvature. The first target may also have a curvature. The curvature of the first reflector may be less than the curvature of the first target. The target may have a shape of a cylindrical, corrugated, or foil portion. The apparatus may also have a second reflector similar in some or all respects to the first reflector. The apparatus may also have a second target similar in some or all respects to the first target. In this case, the first and second targets may be separated by a gap between their leading edges and/or a gap between their trailing edges. It is also possible for the leading edges to touches and for the trailing edges to touches.

According to an embodiment of the present invention, an apparatus for ionizing air has a first reflector and a target. The first reflector receives direct UV energy from a first UV emitter and reflects this UV energy. The first reflector may be a specular reflector and may be parabolic. The target has a first face that also receives direct UV energy from the first UV emitter as well as the reflected UV energy from the first reflector. Furthermore, the target has a second face that receives direct UV energy from a second UV emitter. These faces are coated with a photo-catalytic coating. The apparatus may also have a second reflector that receives direct UV energy from the second UV emitter and reflects this UV energy towards the second face of the target.

According to an embodiment of the present invention, a method for ionizing air includes: receiving, at an inner face of a first target, UV energy from a UV emitter; responsively generating ions at a photo-catalytic coating on the inner face of the first target; reflecting, at a first reflector, UV energy from the UV emitter to form reflected UV energy; receiving, at an outer face of the first target, reflected UV energy from the first reflector; and responsively generating ions at a photo-catalytic coating on the outer face of the first target. The method may also include one or more of the following: passing, through a plurality of passages in the first target, UV energy from the UV emitter and towards the first reflector; passing an airflow over the inner and outer faces of the first target to carry the ions away from the first target; receiving, at an inner face of a second target, UV energy from a UV emitter; responsively generating ions at a photo-catalytic coating on the inner face of the second target; reflecting, at a second reflector, UV energy from the UV emitter to form reflected UV energy; receiving, at an outer face of the second target, reflected UV energy from the second reflector; responsively generating ions at a photo-catalytic coating on the outer face of the second target; passing, through a plurality of passages in the first target, UV energy from the UV emitter and towards the first reflector; passing, through a plurality of passages in the second target, UV energy from the UV emitter and towards the second reflector; passing an airflow over the inner and outer faces of the first target to carry the ions away from the first target; and passing the airflow over the inner and outer faces of the second target to carry the ions away from the second target.

According to an embodiment of the present invention, a method for ionizing air includes: receiving, at a first face of a target, ultra-violet (“UV”) energy from a first UV emitter; responsively generating ions at a photo-catalytic coating on the first face of the target; reflecting, at a first reflector, UV energy from the first UV emitter to form reflected UV energy; receiving, at the first face of the target, reflected UV energy from the first reflector; and responsively generating ions at the photo-catalytic coating on the first face of the target. The method may also include one or more of the following: passing an airflow over the first face of the target to carry the ions away from the target; receiving, at a second face of the target, UV energy from a second UV emitter; responsively generating ions at a photo-catalytic coating on the second face of the target; reflecting, at a second reflector, UV energy from the second UV emitter to form reflected UV energy; receiving, at the second face of the target, reflected UV energy from the second reflector; responsively generating ions at the photo-catalytic coating on the second face of the target; and passing an airflow over the first and second faces of the target to carry the ions away from the target.

According to an embodiment of the present invention, an apparatus for ionizing air has a first foil target portion and a second foil target portion. Each of the foil target portions has passages and an inner face that receives direct UV energy from a UV emitter. The inner faces are coated with a photo-catalytic coating. The leading edges of the foil target portions may be touching or separated by a gap. Similarly, the trailing edges of the foil target portions may be touching or separated by a gap.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a perspective view of a photo-catalytic cell, according to an embodiment of the present invention.

FIG. 2 shows a side elevation view of a photo-catalytic cell, according to an embodiment of the present invention.

FIG. 3 shows a cross-sectional view of the photo-catalytic cell of FIG. 2 taken along the line 3-3, according to an embodiment of the present invention.

FIG. 4 shows a graph illustrating a difference in performance of a photo-catalytic cell with and without UV reflectors, according to an embodiment of the present invention.

FIGS. 5-11 show various apparatuses for ionizing air, according to embodiments of the present invention.

FIG. 12 shows a flowchart of a method for ionizing air, according to an embodiment of the present invention.

FIG. 13 shows a flowchart of a method for ionizing air, according to an embodiment of the present invention.

The foregoing summary, as well as the following detailed description of certain embodiments of the present invention, will be better understood when read in conjunction with the appended drawings. For the purposes of illustration, certain embodiments are shown in the drawings. It should be understood, however, that the claims are not limited to the arrangements and instrumentality shown in the attached drawings. Furthermore, the appearance shown in the drawings is one of many ornamental appearances that can be employed to achieve the stated functions of the system.

DETAILED DESCRIPTION OF THE INVENTION

The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention. Various inventive features are described below that can be used independently of one another or in combination with other features.

Broadly, embodiments of the present invention generally provide a photo-catalytic cell in which one or more reflectors may be positioned to reflect UV energy and increase a proportion of emitted UV energy that strikes a target in the cell at high incident angles.

Referring to FIGS. 1-3, a photo-catalytic cell 10 may include an electronics box 12, a light pipe indicator 14, a power cord 16, a chamber 18, honeycomb targets 20, UV reflectors (22-1, 22-2, and 22-3), and a UV emitter or lamp 24. The honeycomb targets 20 may be coated with titanium dioxide.

Airflow may pass across the honeycomb targets 20 while UV energy may be applied to the target 20 by the lamp 24. A photo-catalytic reaction may take place in the presence of the UV energy. The reaction may produce bactericidal molecules in the air.

Referring to FIG. 3, the efficacy of the UV reflectors 22-1 may be illustrated. If a reflector 22-1 is not present, an emitted ray 26 might pass through the honeycomb target 20 without impinging on the titanium dioxide. However, when one of the reflectors 22-1 is present, an illustrative emitted ray 28-1 of UV energy may impinge on the UV reflectors 22-1. The ray 28-1 may be reflected to become a reflected ray 28-2. It may be seen that the reflected ray 28-2 may impinge on a surface of the honeycomb target 20. It may be seen that a hypothetical unreflected ray 26, which might follow a path parallel to that of the ray 28-1, might pass through the honeycomb target 20 without impinging on the target 20. Thus, presence of the reflector 22-1 in the path of the ray 28-1 may result in avoidance of loss of the UV energy from the ray 28-1. The reflectors 22-1 may be relatively small as compared to the size of the honeycomb target 20. The small size (about 10% of the size of the target 20) may allow for minimal airflow obstruction. In spite of their relatively small size, the reflectors 22-1 may be effective because they may reflect virtually all of the (normally lost) UV energy that is emitted in a direction that is almost orthogonal (e.g., within ±5° of orthogonality) to the outer vertical plane of the honeycomb target 20. Hence, UV energy may pass through the honeycomb target 20 without touching the titanium dioxide surface. But by reflecting the UV rays onto the opposite side target matrix, that energy could be captured and utilized so as to add to the total ion count within the desired cloud of ionized molecules. In other words, the number of ions created by any incoming UV ray is proportional to the sine of the incident angle θ between the UV ray path and the titanium dioxide surface that a given ray is impacting, as illustrated by the following trigonometric relationships:

For θ = 90° Sin(θ) = 1 Maximum energy gathered For θ = 0° Sin(θ) = 0 Minimum energy gathered

Reflectors 22-3 may be interposed between the lamp 24 and walls of the chamber 18. UV energy striking the reflectors 22-3 may be reflected onto the honeycomb target 20. Thus presence of the reflectors 22-3 may result in avoidance of loss of UV energy that might otherwise be absorbed or diffused by walls of the chamber 18. Similarly, reflectors 22-2 may be placed in corners of the chamber 18 to reflect UV energy onto the honeycomb target 20.

The reflectors 22-1, 22-2, and/or 22-3 may be constructed from material that is effective for reflection of energy with a wavelength in the UV range (e.g., about 184-255 nm). While soft metals such as gold and silver surfaces may be effective reflectors for visible light, their large grain size may make them less suitable than metallic surfaces with a small grain size (e.g., hard metals). Thus, hard metals such as chromium and stainless steel and other metals that do not readily oxidize may be effective UV reflectors and may be particularly effective for use as UV reflectors in a photo-catalytic cell. Material with a UV reflectivity of about 90% or higher may be suitable for use in the reflectors 22-1, 22-1 and/or 22-3. Lower reflectively produces lower effectiveness. To achieve the level of reflection required, it may be necessary to micro-polish or buff a selected materials reflective surface.

Reflecting surfaces of the reflectors 22 may be electrically conductive and/or grounded. Specifically, surface coatings (added for oxidation protection) like glass, clear plastics, or clear anodization (e.g., non-conductive) may diminish any performance enhancement of a photo-catalytic cell.

Also, reflecting surfaces of the UV reflector 22 may produce surface specular reflection. Specular reflection may be, for example, a mirror-like reflection of light in which a single incoming light ray is reflected into a corresponding single outgoing direction. Specular reflection is distinct from diffuse reflection, in which a single incoming light ray is reflected into a broad range of directions. Diffuse reflection may diminish performance enhancement of a photo-catalytic cell.

In an embodiment of the photo-catalytic cell 10, the reflectors 22-1, 22-2 and 22-3 may be chromium-plated plastic. Chromium-plated plastic may be a relatively low cost material with a relatively high degree of reflectivity for UV energy. So-called soft chrome, such as the plating used to produce a mirror-like finish that is seen on automobile chromed surfaces, may be employed.

It may be noted that there may be other cell shape designs which are not rectangular. For example, the cell 10 may be circular, tubular, or may have an otherwise complex shape. For these non-rectangular shaped cells, an optimum reflector design may be curved or otherwise non-flat in shape.

Referring to FIG. 5, an apparatus 500 for ionizing air is shown according to an embodiment of the present invention. The apparatus 500 includes a UV emitter 510, a target 520, and a reflector 530.

The UV emitter 510 may emit direct UV energy (e.g., 184-255 nm wavelengths). The UV emitter 510 may be a lamp (e.g., fluorescent, LED, laser gas-discharge, etc.). The target 520 may have an inner face 522 and an outer face 524. The inner face 522 may be arranged to face or to receive direct UV energy from the UV emitter 510.

The reflector 530 may receive direct UV energy from the UV emitter 510. The target 520 may have passages between the inner and outer faces 522, 524. As an example, the passages may be slits (e.g., ½″ long) or holes (e.g., ¼″ diameter). Such slits may be horizontally arranged (as shown) or transversely arranged (e.g., from leading edge towards trailing edge). There may be a distance between each passage (e.g., ½″ for the horizontal arrangement or ¾″ for the transverse arrangement). The passages may be in rows. For example, the rows may be separated from each other by ½″. The passages may have a thickness, such as the thickness of a nickel.

The direct UV energy may pass through these passages and towards the reflector 530. The reflector may reflect this direct UV energy, and the outer face 524 of the target 520 may be arranged to receive this reflected UV energy. The reflector 530 may include a specular reflector and may specularly reflect the UV energy. The specular reflector may be grounded.

The inner and outer faces 522, 524 of the target 520 may be coated with a photo-catalytic coating such as, for example, a coating that includes TiO₂ that facilitates the generation of ions in response to receiving the UV energy (direct and reflected).

Referring to FIG. 6, an apparatus 600 for ionizing air is shown according to an embodiment of the present invention. The apparatus 600 may be, in many respects, similar to the apparatus 500. The apparatus 600 may include a UV emitter 610, a first target 620, a first reflector 630, a second target 640, and a second reflector 650. The second target 640 may be opposite the first target 620. The second reflector 650 may be opposite the first reflector 630.

Both targets 620, 640 may have inner and outer faces coated with a photo-catalytic coating to facilitate the generation of ions in response to receiving UV energy. Both reflectors 630, 650 may include specular reflectors. The inner faces of the targets 620, 640 may receive direct UV energy from the UV emitter 610. The reflectors 630, 650 may also receive direct UV energy from the UV emitter 510. For example, direct UV energy may pass through passages in the targets 620, 640 to reach the reflectors 630, 650. The reflected UV energy from the reflectors 630, 650 may be received at outer faces of the targets 620, 640.

The inner and outer faces of the targets 620, 640 may be coated with a photo-catalytic coating such as, for example, a coating that includes TiO₂ that facilitates the generation of ions in response to receiving the UV energy (direct and reflected).

One or both of the targets 620, 640 may have a curvature. For example, the target(s) 620, 640 may have a shape of a cylindrical portion. One or both of the reflectors 630, 650 may also have a curvature. The curvature of the target(s) 620, 640 may be greater than the curvature of the reflector(s) 630, 650.

The targets 620, 640 each may have a leading edge and a trailing edge. The leading edges may be upstream of an airflow from the trailing edges. The leading edge of the first target 620 may be separated from the leading edge of the second target 640 by a leading edge gap (as illustrated). Alternatively, the leading edges may be connected or abutting. Similarly, the trailing edge of the first target 620 may be separated from the trailing edge of the second target 640 by a trailing edge gap, or the trailing edges may be connected or abutting.

Referring to FIGS. 6-8, different target and reflector shapes are illustrated. The targets may have cylindrical portions (e.g., targets 620, 640 in FIG. 6). The targets may have corrugated portions (e.g., targets 720, 740 in FIG. 7). For example, a corrugated portion may have two peaks and two or three valleys. The targets may have foil portions (e.g., 820, 840 in FIG. 8). Other target shape variations are also possible. The shapes of the first and second targets may be different from each other.

The targets may have cylindrical portions (e.g., targets 620, 640 in FIG. 6). The targets may have corrugated portions (e.g., targets 720, 740 in FIG. 7). The targets may have foil portions (e.g., targets 820, 840 in FIG. 8). Other target shape variations are also possible. The shapes of the first and second targets may be different from each other.

The reflectors may be curved (e.g., reflectors 630, 650 in FIG. 6) or flat (e.g., reflectors 730, 750 in FIG. 7 or reflectors 830, 850 in FIG. 8). Other reflector shape variations are also possible. The shapes of the first and second reflectors may be different from each other.

Referring to FIG. 10, an apparatus 1000 may have a first UV emitter 1010, a second UV emitter 1012, a target 1020, a first reflector 1040, and a second reflector 1050. The target may have a first face that is arranged to receive direct UV energy from the first UV emitter. The target may also have a second face arranged to receive direct UV energy from a second UV emitter. The faces of the target may be coated with a photo-catalytic coating.

The first reflector may receive direct UV energy from the first UV emitter and reflect it towards the first face of the target. The second reflector may receive direct UV energy from the second UV emitter and reflect it towards the second face of the target. The reflectors may be specular reflectors and may be grounded. The reflectors may be parabolic (see FIG. 11). A parabolic reflector may be helpful to reflect UV energy in a direction orthogonal to the target 1020.

FIG. 12 shows a flowchart 1200 of a method for ionizing air, according to an embodiment of the present invention. The flowchart 1200 may be performable, for example, with an apparatus such as the ones shown in FIGS. 5-8. Furthermore, the flowchart 1200 may be performable in a different order, or some steps may be omitted according to design or preferences.

At step 1202, UV energy is received from a UV emitter at inner face(s) of a first and/or second target. At step 1204, ions are responsively generated at a photo-catalytic coating on the inner face(s) of the target(s). At step 1206, UV energy is passed from the UV emitter and towards a first and/or second reflector, through a plurality of passages in the target(s). At step 1208, UV energy is reflected from the UV emitter at the reflector(s) to form reflected UV energy. At step 1210, reflected UV energy is received from the reflector(s) at outer face(s) of the target(s). At step 1212, ions are responsively generated at a photo-catalytic coating on the outer face(s) of the target(s). At step 1214, an airflow is passed over the inner and outer face(s) of the target(s) to carry the ions away from the target(s).

FIG. 13 shows a flowchart 1300 of a method for ionizing air, according to an embodiment of the present invention. The flowchart 1300 may be performable, for example, with an apparatus such as the ones shown in FIGS. 10 and 11. Furthermore, the flowchart 1300 may be performable in a different order, or some steps may be omitted according to design or preferences.

At step 1302, UV energy is received from a first and/or second UV emitter at a first and/or second face of a target. At step 1304, ions are responsively generated at a photo-catalytic coating on the face(s) of the target. At step 1306, UV energy is reflected from the UV emitter(s) at a first and/or second reflector to form reflected UV energy. At step 1308, reflected UV energy is received from the reflector(s), at the face(s) of the target. At step 1310, ions are responsively generated at the photo-catalytic coating on the face(s) of the target. At step 1312, an airflow is passed over the face(s) of the target to carry the ions away from the target.

FIGS. 9A and 9B show an apparatus 900 for ionizing air, according to an embodiment of the present invention. The apparatus 900 may be similar, in some respects, to apparatus 800 shown in FIG. 8. The apparatus 900 may include a UV emitter 910, a first foil target portion 920, and a second foil target portion 940. One or each of the foil target portions 920, 940 may have an inner face arranged to receive direct UV energy from the UV emitter 910. One or each of the foil target portions 920, 940 may have a plurality of passages and may be coated with a photo-catalytic coating on the inner face. The leading edges of the foil portions may be touching (e.g., abutting, connecting, integrated) or may be separated by a leading edge gap. The trailing edges of the foil portions may abut or may be separated by a trailing edge gap. The apparatus 900 may also have one or more reflectors 930 arranged on or near the inner faces of the first or second foil target portions. Such reflectors 930 may also be used in combination with other reflectors, such as those shown in FIGS. 5-8.

Turbulence may tend to destroy cluster ions. A foil-shaped target may be useful to reduce turbulence as airflow passes over. Other turbulence-reducing techniques may include the use of an air straightener upstream from a leading edge of a target. Furthermore, higher airflow speeds may be useful for efficiently generating cluster ions but not oxidizers. The foil design may accelerate the airflow to improve the efficiency of this process.

While the invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. 

1. An apparatus for ionizing air, the apparatus comprising: a first reflector arranged to: receive direct ultra-violet (“UV”) energy from a first UV emitter, and reflect the direct UV energy from the first UV emitter to form reflected UV energy; a target including: a first face arranged to: receive direct UV energy from the first UV emitter, and receive the reflected UV energy from the first reflector; and a second face arranged to receive direct UV energy from a second UV emitter; and a photo-catalytic coating on the first and second faces of the target.
 2. The apparatus of claim 1, wherein the first reflector comprises a specular reflector.
 3. The apparatus of claim 1, wherein the first reflector comprises a parabolic reflector.
 4. The apparatus of claim 1, further comprising: a second UV reflector arranged to: receive direct UV energy from the second UV emitter, and reflect the direct UV energy from the second UV emitter to form reflected UV energy; and wherein the second face of the target is arranged to receive reflected UV energy from the second UV reflector.
 5. The apparatus of claim 4, wherein the first and second reflectors comprise specular reflectors.
 6. The apparatus of claim 4, wherein the first and second reflectors comprise parabolic reflectors.
 7. A method for ionizing air, the method comprising: receiving, at an inner face of a first target, ultra-violet (“UV”) energy from a UV emitter; responsively generating ions at a photo-catalytic coating on the inner face of the first target; specularly reflecting, at a first reflector, UV energy from the UV emitter to form specularly reflected UV energy; receiving, at an outer face of the first target, specularly reflected UV energy from the first reflector; and responsively generating ions at a photo-catalytic coating on the outer face of the first target.
 8. The method of claim 7, further comprising passing, through a plurality of passages in the first target, UV energy from the UV emitter and towards the first reflector.
 9. The method of claim 8, further comprising passing an airflow over the inner and outer faces of the first target to carry the ions away from the first target.
 10. The method of claim 7, further comprising: receiving, at an inner face of a second target, UV energy from a UV emitter; responsively generating ions at a photo-catalytic coating on the inner face of the second target; specularly reflecting, at a second reflector, UV energy from the UV emitter to form specularly reflected UV energy; receiving, at an outer face of the second target, specularly reflected UV energy from the second reflector; and responsively generating ions at a photo-catalytic coating on the outer face of the second target.
 11. The method of claim 10, further comprising: passing, through a plurality of passages in the first target, UV energy from the UV emitter and towards the first reflector; and passing, through a plurality of passages in the second target, UV energy from the UV emitter and towards the second reflector.
 12. The method of claim 11, further comprising: passing an airflow over the inner and outer faces of the first target to carry the ions away from the first target; and passing the airflow over the inner and outer faces of the second target to carry the ions away from the second target
 13. A method for ionizing air, the method comprising: receiving, at a first face of a target, ultra-violet (“UV”) energy from a first UV emitter; responsively generating ions at a photo-catalytic coating on the first face of the target; reflecting, at a first reflector, UV energy from the first UV emitter to form reflected UV energy; receiving, at the first face of the target, reflected UV energy from the first reflector; responsively generating ions at the photo-catalytic coating on the first face of the target; and passing an airflow over the first face of the target to carry the ions away from the target.
 14. The method of claim 13, further comprising: receiving, at a second face of the target, UV energy from a second UV emitter; responsively generating ions at a photo-catalytic coating on the second face of the target; reflecting, at a second reflector, UV energy from the second UV emitter to form reflected UV energy; receiving, at the second face of the target, reflected UV energy from the second reflector; responsively generating ions at the photo-catalytic coating on the second face of the target; and passing an airflow over the first and second faces of the target to carry the ions away from the target.
 15. An apparatus for ionizing air, the apparatus comprising: a first foil target portion including an inner face arranged to receive direct ultra-violet (“UV”) energy from a UV emitter, wherein the first foil target has a plurality of passages; a second foil target portion including an inner face arranged to receive direct UV energy from a UV emitter, wherein the second foil target has a plurality of passages; and a photo-catalytic coating on the inner faces of the first foil target portion and the second foil target portion.
 16. The apparatus of claim 15, wherein a leading edge of the first foil target touches a leading edge of the second foil target; and wherein a trailing edge of the first foil target touches a trailing edge of the second foil target.
 17. The apparatus of claim 15, wherein a gap separates a leading edge of the first foil target from a leading edge of the second foil target; and wherein a gap separates a trailing edge of the first foil target from a trailing edge of the second foil target.
 18. An apparatus for ionizing air, the apparatus comprising: a first target including: an inner face arranged to receive ultra-violet (“UV”) energy from a UV emitter, an outer face, a plurality of passages between the inner face and the outer face, and a photo-catalytic coating on the plurality of passages; a first reflector configured to reflect UV energy from the UV emitter towards the photo-catalytic coating of the first target, wherein the first reflector is a specular UV reflector; and wherein the first target is configured to: receive, through the inner face and at the photo-catalytic coating, UV energy from the UV emitter and the first reflector, generate ions in response to the received UV energy, pass an airflow from the inner face and through the plurality of passages to carry the ions away from the outer face. 